It is a dangerous thing when, in the course of engineering, you have a solution looking for a problem, instead of a problem looking for a solution. I'd say that the biggest benefit in using IS-IS over OSPF is the tuning of route metrics, but aside from that, I'd say that the two routing protocols are substantially similar enough to warrant close consideration of exactly what one would want bad enough to switch from one to the other. - ferg -- Erik Haagsman <erik@we-dare.net> wrote: On Tue, 2005-06-21 at 09:04 -0500, Dan Evans wrote:

Can anyone point me to information on what the top N service providers are using for their IGP? I'm trying to build a case for switching from OSPF to IS-IS.

Why are you trying to build a case...? Would you already have operational benefit from switching and are you building a case round that and if not, why switch...? Switching IGP in a non-trivial network isn't something you'd want to do unless you've got a clear motive and it gives you some operational advantage... -- "Fergie", a.k.a. Paul Ferguson Engineering Architecture for the Internet fergdawg@netzero.net or fergdawg@sbcglobal.net ferg's tech blog: http://fergdawg.blogspot.com/